Fuel system for a vehicle

ABSTRACT

A natural gas system for a vehicle includes a fuel pod, a conduit defining a flow path, a fuel control module, and an accumulator. The fuel pod includes a fuel tank configured to store natural gas. The conduit includes a first end coupled to the fuel pod and a second end configured to be coupled to an engine. The fuel control module is disposed along the flow path and configured to regulate a flow of natural gas to the engine. The accumulator is disposed along the flow path downstream of the fuel control module. The accumulator is configured to buffer variations in the flow of natural gas such that the engine receives a consistent flow of natural gas.

BACKGROUND

Refuse vehicles collect a wide variety of waste, trash, and othermaterial from residences and businesses. Operators use the refusevehicle to transport the material from various waste receptacles withina municipality to a storage or processing facility (e.g., a landfill, anincineration facility, a recycling facility, etc.). Refuse vehicles maybe powered by an internal combustion engine that burns gasoline, dieselfuel, or natural gas, among other types of fuel. Where the fuel isnatural gas, various tanks provide fuel to a regulator, which reducesthe pressure of the natural gas before it enters the engine. Mechanicalregulators provide an inconsistent flow of natural gas that varies basedupon the pressure of the fuel in the natural gas tanks. The natural gastanks may be positioned above the roof of the body assembly. To isolatethe natural gas tanks, an operator boards the refuse vehicle and engagesvalves positioned at the head of each tank. Despite these deficiencies,assemblies that provide variations in the natural gas flow and includetanks that must be individually isolated remain the primary fuel systemsfor natural gas powered refuse vehicles.

SUMMARY

One embodiment of the invention relates to a natural gas system for avehicle that includes a fuel pod, a conduit defining a flow path, a fuelcontrol module, and an accumulator. The fuel pod includes a fuel tankconfigured to store natural gas. The conduit includes a first endcoupled to the fuel pod and a second end configured to be coupled to anengine. The fuel control module is disposed along the flow path andconfigured to regulate a flow of natural gas to the engine. Theaccumulator is disposed along the flow path downstream of the fuelcontrol module. The accumulator is configured to buffer variations inthe flow of natural gas such that the engine receives a consistent flowof natural gas.

Another embodiment of the invention relates to a natural gas system fora vehicle that includes a tank configured to provide a supply flow ofnatural gas, a conduit defining a flow path, a valve disposed along theflow path, and a controller. The conduit includes a first end coupled tothe tank and a second end configured to be coupled to an engine. Thevalve is configured to provide a regulated flow of natural gas to theengine by adjusting the supply flow of natural gas. The controller isconfigured to evaluate a target pressure for the regulated flow ofnatural gas and selectively engage the valve such that the enginereceives natural gas at the target pressure.

Still another embodiment of the invention relates to a vehicle thatincludes a chassis, a body assembly, and a natural gas fuel system. Thechassis includes an engine coupled to a frame. The body assembly iscoupled to the frame and includes a plurality of sidewalls and an upperwall. The natural gas fuel system includes a fuel pod, a fuel regulator,and a shutoff valve. The fuel pod includes a plurality of natural gasfuel tanks positioned along the upper wall of the body assembly, and thefuel pod is coupled to the engine with a plurality of conduits thatdefine a flow path. The fuel regulator is disposed along the flow pathand configured to regulate a flow of natural gas to the engine. Theshutoff valve is disposed along the flow path between the fuel pod andthe fuel regulator, and the shutoff valve is coupled to a lower portionof the body assembly such that an operator standing alongside thevehicle may isolate the fuel pod by engaging the shutoff valve.

The invention is capable of other embodiments and of being carried outin various ways. Alternative exemplary embodiments relate to otherfeatures and combinations of features as may be recited in the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure will become more fully understood from the followingdetailed description, taken in conjunction with the accompanyingfigures, wherein like reference numerals refer to like elements, inwhich:

FIG. 1 is a side plan view of a refuse vehicle including a fuel pod,according to an exemplary embodiment;

FIG. 2 is a schematic view of a natural gas system for a vehicle,according to an exemplary embodiment;

FIG. 3A is a side plan view of an accumulator for a natural gas system,according to one embodiment;

FIG. 3B is a side plan view of an accumulator for a natural gas system,according to an alternative embodiment;

FIG. 4 is a side plan view of an accumulator for a natural gas system,according to an alternative embodiment;

FIG. 5 is a side plan view of an accumulator for a natural gas system,according to an alternative embodiment;

FIG. 6 is a schematic view of a natural gas system including a manifoldand a fuel pod having a plurality of fuel tanks, according to oneembodiment;

FIG. 7 is a schematic view of a natural gas system including a manifoldand a fuel pod having a plurality of fuel tanks, according to analternative embodiment;

FIG. 8 is a schematic view of a manifold for a natural gas systemincluding a shutoff valve, according to an exemplary embodiment;

FIG. 9 is a schematic view of a natural gas system including a pair ofpressure transducers and a filter, according to one embodiment;

FIG. 10 is a schematic view of a natural gas system including a pair ofpressure transducers and a filter, according to an alternativeembodiment;

FIG. 11 is a schematic view of a natural gas system including a valvethat regulates the flow of natural gas, according to one embodiment;

FIG. 12 is a schematic view of a natural gas system including a valvethat regulates the flow of natural gas, according to an alternativeembodiment;

FIG. 13 is a side plan view of a refuse vehicle including a fuel pod, avalve, a user access panel, and a pressure regulator, according to anexemplary embodiment;

FIG. 14 is a perspective view of a body assembly for a refuse vehicleincluding a fuel pod, a valve, and a user access panel, according to anexemplary embodiment;

FIG. 15 is another perspective view of a body assembly for a refusevehicle including a fuel pod, a valve, and a user access panel,according to an exemplary embodiment;

FIG. 16 is another perspective view of a body assembly for a refusevehicle including a fuel pod, a valve, and a user access panel,according to an exemplary embodiment; and

FIG. 17 is a schematic view of a natural gas system including a useraccess panel that is separated from a fuel regulator, according to anexemplary embodiment.

DETAILED DESCRIPTION

Before turning to the figures, which illustrate the exemplaryembodiments in detail, it should be understood that the presentapplication is not limited to the details or methodology set forth inthe description or illustrated in the figures. It should also beunderstood that the terminology is for the purpose of description onlyand should not be regarded as limiting.

Referring to the exemplary embodiment shown in FIG. 1, a vehicle, shownas refuse truck 10 (e.g., garbage truck, waste collection truck,sanitation truck, etc.), includes a chassis, shown as chassis 20.According to an alternative embodiment, the vehicle is another type ofvehicle (e.g., a concrete mixer truck, a military truck, etc.). Chassis20 includes a pair of longitudinal frame rails extending along thelength of refuse truck 10, according to an exemplary embodiment. In oneembodiment, the prime mover provides power to various systems of refusetruck 10. By way of example, the prime mover may provide power to one ormore tractive elements, shown as wheels 22, to move refuse truck 10. Byway of another example, the prime mover may provide power to a pneumaticsystem, a hydraulic system, or still another system. A power take offunit may facilitate such power distribution.

Referring again to the exemplary embodiment shown in FIG. 1, refusetruck 10 includes a cab, shown as cab 24, that is coupled to chassis 20.Cab 24 includes various components to facilitate operation of refusetruck 10 by an operator (e.g., a seat, a steering wheel, hydrauliccontrols, etc.). Cab 24 is positioned at a front end of refuse truck 10.In other embodiments, the cab is otherwise positioned.

According to the embodiment shown in FIG. 1, refuse truck 10 includes abody assembly coupled to chassis 20. The body assembly includes astorage body, shown as body 26, that extends along the length of chassis20 and is positioned behind cab 24. In other embodiments, body 26 isotherwise positioned. Refuse is stored within body 26 during transportfrom various waste receptacles within a municipality to a storage orprocessing facility (e.g., a landfill, an incineration facility, arecycling facility, etc.). A packing assembly may be positioned withinbody 26 to compact the loose refuse, thereby increasing the storagecapacity of body 26. In one embodiment, body 26 includes an upper doorto reduce the likelihood of loose refuse blowing out of body 26 duringtransport. As shown in FIG. 1, the body assembly also includes an armhaving lift forks that engage a container to load refuse into body 26.

Referring still to FIG. 1, chassis 20 includes a prime mover, shown asengine 30, a drive train, hydraulic components (e.g., a hydraulic pump,etc.), and still other components to facilitate the operation of refusetruck 10. According to an exemplary embodiment, engine 30 is an internalcombustion engine configured to generate mechanical power by ignitingnatural gas. As shown in FIG. 1, refuse truck 10 includes a fuel pod,shown as fuel pod 40. In one embodiment, fuel pod 40 is configured tostore compressed natural gas (CNG). In another embodiment, fuel pod 40is configured to store liquefied natural gas (LNG). Fuel pod 40 includesa fuel tank that is configured to store fuel (e.g., natural gas) for usein engine 30. In one embodiment, the fuel tank contains CNG. In anotherembodiment, the fuel tank contains LNG. The fuel tank may be configuredto store CNG or LNG under preferred conditions (e.g., pressure,temperature, etc.). In one embodiment, the fuel tank is configured tostore CNG at a tank pressure (e.g., 3,600 PSI, etc.). According to anexemplary embodiment, the fuel tank is configured to store CNG, and atank wrapping is positioned around the fuel tank. The tank wrappingallows an operator to determine whether the tank has been struck (e.g.,by road debris, by a tree branch, etc.). An operator may further inspecta tank that has been struck (e.g., to check for damage). According to anexemplary embodiment, the tank wrapping includes a pair of clam shellsmanufactured from moldable polyurethane sheets. According to analternative embodiment, the tank wrapping is a film covering at least aportion of the tank. In other embodiments, the prime mover includes oneor more electric motors. The electric motors may consume electricalpower from an on-board energy storage device (e.g., batteries,ultra-capacitors, etc.), from an on-board generator (e.g., an internalcombustion engine, a fuel cell, etc.), from an external power source(e.g., overhead power lines, etc.), or still another source and providepower to the systems of the refuse truck 10. Fuel pod 40 may store fuelfor use by the on-board generator.

Referring next to the exemplary embodiment shown in FIG. 2, a naturalgas system for a vehicle, shown as natural gas system 50, includes fuelpod 40, a fuel control module 60, and an accumulator 70. In oneembodiment, the vehicle is a refuse truck. In another embodiment, thevehicle is another type of vehicle (e.g., a concrete mixer truck, amilitary truck, etc.). According to an exemplary embodiment, natural gassystem 50 is configured to provide natural gas to engine 30. Engine 30may combust the natural gas to power one or more tractive elements. Inother embodiments, engine 30 combusts the natural gas to generateelectricity or power a component of refuse truck 10. According to stillother embodiments, natural gas system 50 is configured to providenatural gas for use by another component of refuse truck 10 (e.g., afuel cell).

According to an exemplary embodiment, fuel control module 60 includes apressure regulator configured to reduce the pressure of the natural gasfrom the tank pressure to a working pressure. In one embodiment, aheater (e.g., an electric heater) is coupled to the pressure regulator.The heater reduces the risk of freezing the valve due to the temperaturedecrease of the expanding natural gas. In one embodiment, the heater iscontrolled with a controller. The controller may operate according to apredetermined schedule (e.g., when the vehicle is running, a cycle of onfor five minutes and off for five minutes, etc.) or may operate when acondition of the valve reaches a threshold value (e.g., when the valvetemperature falls below 40 degrees Fahrenheit based on sensor signalsfrom a temperature sensor, etc.). In still another embodiment, heat tapeis wrapped around the pressure regulator, thereby reducing the risk offreezing the valve.

As shown in FIG. 2, fuel pod 40 is coupled to (e.g., in fluidcommunication with, etc.) fuel control module 60 with a conduit (i.e.pipe, hose, duct, line, tube, etc.), shown as high-pressure line 80.Fuel control module 60 is coupled to accumulator 70 and engine 30 with asecond conduit, shown as low-pressure line 90, and a third conduit,shown as low-pressure line 100, according to an exemplary embodiment.The pressure regulator of fuel control module 60 reduces the pressure ofthe natural gas in high-pressure line 80 to provide natural gas alonglow-pressure line 90 and low-pressure line 100 at the working pressure.Fuel control module 60 may also include various other components (e.g.,a fueling receptacle, pressure transducer coupled to a fuel gauge,high-pressure filter, etc.).

High-pressure line 80, low-pressure line 90, and low-pressure line 100define a flow path between fuel pod 40 and engine 30. In one embodiment,fuel flows from fuel pod 40 to engine 30, and accumulator 70 ispositioned along the flow path downstream of fuel control module 60. Inother embodiments, fuel pod 40 is coupled to a first end of a conduitthat defines a flow path, the conduit having a second end that isconfigured to be coupled to an engine. Fuel control module 60 may bedisposed along the flow path, and accumulator 70 may be disposed alongthe flow path downstream of fuel control module 60.

Fuel control module 60 may provide natural gas to low-pressure line 90at a flow rate and pressure that varies based on a characteristic of thenatural gas from fuel pod 40 (e.g., the pressure of the natural gas fromfuel pod 40, the flow rate of natural gas from fuel pod 40, etc.). Asnatural gas in fuel pod 40 is depleted during use, the tank pressure andflow rate decreases. Various other factors may also contribute tovariations in the inlet flow of natural gas (e.g., the natural gas inhigh-pressure line 80). Such variations in the inlet flow of natural gasmay cause fluctuations in the stream of natural gas provided by fuelcontrol module 60. By way of example, the fluctuations may include apressure variation, a temperature variation, a flow rate variation, orstill another variation. The fluctuations may be produced due to thephysical interaction of the natural gas with a mechanical regulator offuel control module 60 of for still another reason.

According to an exemplary embodiment, accumulator 70 is configured tobuffer variations in the flow of natural gas such that engine 30receives a consistent flow of natural gas (e.g., a flow of natural gasthat varies within ten percent of a target flow rate, a flow of naturalgas that varies within ten percent of a target pressure, etc.). By wayof example, accumulator 70 may be configured to buffer pressurevariations in the flow of natural gas such that engine 30 receives aflow of natural gas having a consistent pressure. By way of anotherexample, accumulator 70 may be configured to buffer flow rate variationssuch that engine 30 receives natural gas at a consistent flow rate.During operation, pressure variations, flow rate variations, or stillother variations may cause the power produced by engine 30 to fluctuate.Power fluctuations may be undesirable where, by way of example, engine30 powers tractive elements of a refuse truck. In one embodiment,accumulator 70 includes a drain and is positioned at a low heightrelative to the other components of natural gas system 50. Such aposition and drain allows for oil and other contaminants to be drainedfrom natural gas system 50.

Referring next to the exemplary embodiments shown in FIGS. 3A-3B,accumulator 70 is a reservoir that includes an inlet, shown as inlet 72,and an outlet, shown as outlet 74, defined within a housing 76. As shownin FIGS. 3A-3B, housing 76 has a rectangular cross-sectional shape. Inother embodiments, housing 76 is otherwise shaped (e.g., cylindrical,spherical, etc.). Housing 76 defines an inner volume that may be fixedor variable. In one embodiment, inlet 72 is configured to be coupled tofuel control module 60 and outlet 74 is configured to be coupled toengine 30. In another embodiment, outlet 74 is configured to be coupledto still another component of natural gas system 50 (e.g., ahigh-pressure coalescing filter, etc.).

Natural gas flows along a flow path through accumulator 70, according toan exemplary embodiment. The flow path may be defined between inlet 72and outlet 74 through the inner volume of housing 76. A flow of naturalgas entering inlet 72 may include one or more fluctuations. By way ofexample, the pressure, temperature, or flow rate, among othercharacteristics, of the flow entering inlet 72 may vary as a function oftime. According to an exemplary embodiment, the inner volume of housing76 contains a volume of natural gas that buffers fluctuations inpressure, temperature, or flow rate of natural gas flow through inlet72. By way of example, a pressure fluctuation acting on natural gas atinlet 72 is dissipated as it propagates through the natural gas withinthe inner volume of housing 76 such that the pressure fluctuation isreduced or eliminated at outlet 74. According to another exemplaryembodiment, an interaction between the flow of natural gas and an innersurface of housing 76 dissipates pressure variations as the natural gasflows between inlet 72 and outlet 74.

According to an exemplary embodiment, accumulator 70 buffersfluctuations in flow of natural gas through inlet 72 without bufferingset point changes to pressure, temperature, flow rate, or othercharacteristics. By way of example, brief variations in the flow ofnatural gas may include variations in pressure or flow rate caused by amechanical regulator whereas set point changes to pressure or flow ratemay be provided according to a control strategy for the natural gassystem.

As shown in FIG. 3B, accumulator 70 includes a flow buffer, shown asbaffle 78. In one embodiment, baffle 78 is configured to extend thelength of the flow path through accumulator 70, thereby further reducingthe prevalence of fluctuations in the flow of natural gas at outlet 74.In another embodiment, baffle 78 is configured to provide additionalsurface with which the flow of natural gas interacts, thereby furtherreducing the prevalence of fluctuations in flow of natural gas at outlet74. According to the exemplary embodiment shown in FIG. 3B, accumulator70 includes a plurality of baffles 78 arranged parallel to one another.In other embodiments, accumulator 70 includes a single baffle 78 orbaffles 78 that are otherwise arranged. Baffles 78 are flat plates inthe exemplary embodiment shown in FIG. 3B. In other embodiments, baffles78 are otherwise shaped. By way of example, baffles 78 may be curved andarranged for form a coil that defines a spiraled flow path.

Referring next to the exemplary embodiment shown in FIG. 4, accumulator70 includes a supplemental length of conduit. As shown in FIG. 4,natural gas flows from inlet 72 to outlet 74 along a length of conduit.In one embodiment, a length of conduit beyond the length of conduitrequired to couple various components of a natural gas system definesthe supplemental length. By way of example, a fuel control module may beseparated from an engine by a conduit run distance of fifteen feet, andthe fuel control module may be coupled to the engine with a conduithaving a length of twenty feet, the difference between the conduit rundistance and the conduit length defining the supplemental length ofconduit that forms accumulator 70. As shown in FIG. 4, the supplementallength of conduit is coiled. According to an alternative embodiment, thesupplemental length of conduit is otherwise arranged (e.g., looped,arranged in a U-shape, routed along a body or frame of a vehicle, etc.).

Referring next to the exemplary embodiment shown in FIG. 5, accumulator70 includes a movable wall 110 positioned within the inner volume ofhousing 76. Movable wall 110 is actuated to vary the inner volume ofhousing 76, according to an exemplary embodiment. Changing the innervolume of housing 76 varies a buffer level provided by accumulator 70(e.g., the inner volume may be decreased to lower the buffer level, theinner volume may be increased to increase the buffer level, etc.).According to an exemplary embodiment, the buffer level may be lowered toreduce the impact of accumulator 70 on the flow of natural gas. In oneembodiment, the buffer level of accumulator 70 is lowered to increaseresponsiveness and facilitate providing the engine with a variable flowof natural gas (e.g., a flow having a flow rate or pressure that variesbased on a throttle input, etc.).

In one embodiment, the movable wall 110 is a rigid wall that may beactuated to change the inner volume of housing 76. According to theexemplary embodiment shown in FIG. 5, movable wall 110 is a flexiblebladder that may be inflated from position 112 to position 114 ordeflated from position 112 to position 116. Inflating the flexiblebladder to position 114 may decrease the buffer level of accumulator 70while deflating the flexible bladder to position 116 may increase thebuffer level of accumulator 70. Such inflation or deflation of theflexible bladder may be facilitated by a fluid port (e.g., a hydraulicport, a pneumatic port, etc.) and various accumulators, pumps, valves,or other components. The fluid port may be coupled to an air system of avehicle.

According to an exemplary embodiment, the inner volume of housing 76 isactively varied (e.g., by inflating and deflating the flexible bladder,by otherwise actuating movable wall 110, etc.) to counter pressurefluctuations in the flow of natural gas at inlet 72. By way of example,a pressure transducer may detect the pressure of the inlet flow ofnatural gas and provide sensor signals to a controller, and thecontroller may engage an actuator (e.g., a linear actuator, a rotationalactuator, a source of a pressurized fluid, etc.) to generate a pressurewave that interfaces with and dampens the pressure fluctuation.

Referring next to the exemplary embodiments shown in FIGS. 6-7, naturalgas system 50 includes a manifold 120 disposed along the flow pathdefined along high-pressure line 80, which couples fuel pod 40 with fuelcontrol module 60. As shown in FIGS. 6-7, a first conduit, shown ashigh-pressure line 82, couples fuel pod 40 with manifold 120, and asecond conduit, shown as high-pressure line 84, couples manifold 120with fuel control module 60. Manifold 120 includes various componentsconfigured to facilitate the operation of natural gas system 50.According to an alternative embodiment, manifold 120 is positioneddownstream of fuel control module 60 (e.g., between fuel control module60 and engine 30, between fuel control module 60 and accumulator 70,between accumulator 70 and engine 30, etc.).

Referring still to FIGS. 6-7, fuel pod 40 includes a plurality of tanks,shown as tanks 42. In other embodiments, fuel pod 40 includes more orfewer tanks 42. Tanks 42 are configured to store natural gas for use inengine 30, according to an exemplary embodiment. As shown in FIGS. 6-7,each tank 42 includes a shutoff valve 44. Shutoff valve 44 allows anoperator, user, or other personnel to stop the flow of natural gas fromtank 42, according to an exemplary embodiment. As shown in FIGS. 6-7,the flow of natural gas from each tank 42 is combined into a singleoutlet conduit 46 with a plurality of intermediate conduits 48.According to an exemplary embodiment, the single outlet conduit 64interfaces with the various other components of natural gas system 50 toprovide a flow of natural gas to engine 30. In one embodiment, singleoutlet conduit 46 is a separate line that is coupled to high-pressureline 80. In another embodiment, single outlet conduit 46 is defined by aportion of high-pressure line 80 (i.e. high-pressure line 82 may couplemanifold 120 with a union of the plurality of intermediate conduits 48).

As shown in FIG. 8, manifold 120 includes a shutoff valve 122 disposedalong the flow path between fuel pod 40 and fuel control module 60.Closing shutoff valve 122 stops the flow of natural gas from fuel pod40. In one embodiment, shutoff valve 122 includes a ball valve. In otherembodiments, shutoff valve 122 includes another type of valve (e.g., agate valve, etc.). Shutoff valve 122 is manually operated, according toan exemplary embodiment. According to an alternative embodiment, shutoffvalve 122 is actuated electronically (e.g., with a solenoid). Suchelectronic actuation may occur upon user input or as part of a shutoffvalve control strategy.

In one embodiment, natural gas system 50 defines at least a portion ofthe fuel system for a vehicle. Fuel pod 40 may positioned along the roofof a body assembly, according to an exemplary embodiment. In otherembodiments, fuel pod 40 is positioned behind the drum on a concretemixer truck. In still other embodiments, fuel pod 40 is still otherwisepositioned. According to an exemplary embodiment, an operator mayisolate each of the plurality of tanks 42 by closing shutoff valve 122.The position of shutoff valve 122 facilitates simultaneously stoppingthe flow of natural gas from each tank 42 of fuel pod 40. According toan exemplary embodiment, manifold 120 is positioned near fuel pod 40,thereby isolating a greater portion of the high-pressure natural gassystem.

In the event of a fire onboard the vehicle, an operator may need toisolate each tank 42. Conventionally, where several natural gas tanksare positioned along the roof of a vehicle, an operator must climb tothe roof of the vehicle and close valves to individually stop the flowof fuel from the tanks. Shutoff valve 122 facilitates the simultaneousdisengagement of tanks 42, thereby reducing the need for an operator toshut off each tank 42 individually. In one embodiment, manifold 120 ispositioned such that an operator standing alongside the vehicle mayactuate shutoff valve 122, thereby reducing the need for the operator toboard the vehicle to stop the flow of natural gas from tanks 42.

According to the exemplary embodiment shown in FIG. 8, manifold 120includes a defueling valve 124 disposed along the flow path between fuelpod 40 and fuel control module 60. Defueling valve 124 facilitatesremoving fuel from fuel pod 40, according to an exemplary embodiment.According to an alternative embodiment, defueling valve 124 allows anoperator to perform a pressure equalization and transfer natural gas toanother vehicle. Defueling valve 124 is positioned along the outersurface of a body assembly for a vehicle, according to an exemplaryembodiment. As shown in FIG. 8, defueling valve 124 engages a fitting126 (e.g., a quick-release fitting) and a vent 128 to facilitatedefueling and pressure equalization. In one embodiment, defueling valve124 is a three-way ball valve having a first port exposed tohigh-pressure line 82, a second port in fluid communication with vent128, and a third port exposed to fitting 126. The three-way ball valvefacilitates venting natural gas pressure (e.g., through vent 128) withina hose used to defuel or perform a pressure equalization, according toan exemplary embodiment.

Referring next to the exemplary embodiments shown in FIGS. 9-10, naturalgas system 50 includes a filter, shown as high-pressure coalescingfilter 130, positioned downstream of fuel control module 60. As shown inFIG. 9, high-pressure coalescing filter 130 is positioned between fuelcontrol module 60 and accumulator 70. As shown in FIG. 10, high-pressurecoalescing filter 130 is positioned between fuel control module 60 andengine 30. In other embodiments, high-pressure coalescing filter 130 isotherwise positioned (e.g., upstream of fuel control module 60).

According to an exemplary embodiment, high-pressure coalescing filter130 removes contaminants (e.g., oil, debris, etc.) from the flow ofnatural gas before it reaches engine 30. As shown in FIGS. 9-10, naturalgas system 50 includes a first pressure transducer, shown as pressuretransducer 132, positioned upstream of high-pressure coalescing filter130 and a second pressure transducer, shown as pressure transducer 134,positioned downstream of high-pressure coalescing filter 130. Pressuretransducer 132 and pressure transducer 134 measure the upstream anddownstream pressure of the natural gas flowing through high-pressurecoalescing filter 130, respectively.

As shown in FIGS. 9-10, natural gas fuel system 50 includes a controller140. According to an exemplary embodiment, controller 140 is coupled topressure transducer 132 and pressure transducer 134. In one embodiment,pressure transducer 132 and pressure transducer 134 are configured toprovide sensor signals to controller 140 indicating the upstream anddownstream pressure of the natural gas flowing through high-pressurecoalescing filter 130, respectively. In one embodiment, controller 140is configured to evaluate the sensors signals from pressure transducer132 and pressure transducer 134 to determine a pressure differentialacross high-pressure coalescing filter 130. As high-pressure coalescingfilter 130 removes contaminants from the flow of natural gas,high-pressure coalescing filter 130 begins to clog, and the pressuredifferential increases. According to an exemplary embodiment, controller140 is configured to provide a signal 142 when the pressure differentialexceeds a threshold value (e.g., 50 PSI, 90 PSI) (i.e. controller 140provides a service signal). According to an alternative embodiment,signal 142 encodes data relating to an observed pressure differential(e.g., 20 PSI) across high-pressure coalescing filter 130.

In one embodiment, signal 142 is provided to a user interface (e.g., adisplay, a warning light, etc.) to alert an operator that high-pressurecoalescing filter requires service or repair. In other embodiments,signal 142 is provided to still another system or device (e.g., a remotesystem that monitors the performance of the vehicle, a control systemconfigured to limit the performance of the vehicle by entering a “limpmode” to prevent damage once the pressure differential exceeds thethreshold value, etc.). Sending a service signal, a signal that encodesdata, or providing a signal to another system reduces the likelihoodthat damage will occur to various components of the vehicle (e.g.,engine 30, fouling of sensors or plugs, etc.) due to operating naturalgas system 50 with an ineffective or clogged high-pressure coalescingfilter 130.

Referring next to the exemplary embodiments shown in FIGS. 11-12,natural gas system 50 includes a valve 150 disposed along a flow pathdefined by a conduit coupling tank 42 and engine 30. Valve 150 replacesa traditional mechanical regulator, according to an exemplaryembodiment. In one embodiment, valve 150 is actively adjustable andreduces the flow rate fluctuations common with fixed, mechanicalregulators. Such flow rate fluctuations occur as a function of thepressure within tank 42 and may generate power fluctuations in engine30. Tank 42 provides a supply flow of natural gas. According to anexemplary embodiment, valve 150 is configured to provide a regulatedflow of natural gas to engine 30 by adjusting the supply flow of naturalgas. As shown in FIGS. 11-12, a controller 160 is coupled to valve 150.According to an exemplary embodiment, controller 160 is configured toevaluate a target pressure (e.g., 110 PSI) for the regulated flow ofnatural gas and selectively engage valve 150 such that engine 30receives natural gas at the target pressure. Selectively engaging valve150 accounts for pressure variations due to decreased pressure in tank42, losses due to interaction between the natural gas and the conduitsand components of natural gas system 50, or still other conditions.

As shown in FIGS. 11-12, valve 150 includes a movable valve element 152(e.g., a valve spool, a poppet, etc.) that is engaged by an actuator,shown as solenoid 154 (e.g., a proportional solenoid). Movable valveelement 152 is movable between a closed position, shown in FIGS. 11-12,and various open positions where natural gas flows through valve 150.The flow rate, pressure, or other characteristic of the regulated flowof natural gas may vary based on the position of moveable valve element152. As shown in FIGS. 11-12, movable valve element 152 is biased (e.g.,with a resilient member) into a check valve configuration, where fluidflow through valve 150 is stopped.

According to an exemplary embodiment, valve 150 is coupled to acontroller, shown as controller 170. In one embodiment, controller 170is coupled to solenoid 154. Controller 170 may send and receive signals(e.g., electrical pulses) to or from solenoid 154. According to theembodiment shown in FIGS. 11-12, controller 170 is configured to send acommand signal to solenoid 154. Solenoid 154 may actuate moveable valveelement 152 as a function of the command signal. According to anexemplary embodiment controller 170 sends command signals to solenoid154 such that engine 30 receives natural gas at the target pressure.

In one embodiment, controller 170 receives or retrieves the targetpressure for the regulated flow of natural gas. By way of example, anoperator may provide a target pressure using a user interface. By way ofanother example, a remote operation system may provide the targetpressure to controller 170. By way of still another example, the targetpressure may be stored in a memory (i.e. the target pressure may beretrieved by controller 170). Controller 170 may evaluate the targetpressure and selectively engage valve 150.

As shown in FIG. 12, natural gas system 50 includes a sensor, shown aspressure transducer 180. Pressure transducer 180 is disposed along theflow path downstream of valve 150. According to an exemplary embodiment,pressure transducer 180 is configured to provide sensor signals relatingto the pressure of the regulated flow of natural gas. According to anexemplary embodiment, pressure transducer 180 is positioned along theflow path near engine 30 such that pressure transducer 180 reads thepressure of the natural gas as it flows into engine 30. By way ofexample, the pressure of the regulated flow of natural gas may be at thetarget pressure near the output of valve 150 but decrease due to linelosses as it travels to engine 30. Positioning pressure transducer 180along the flow path near engine 30 reduces the error that may otherwisebe associated with such line loses and reduces the risk of providingengine 30 with a flow of natural gas below the target pressure.

In one embodiment, controller 170 is configured to evaluate the sensorsignals as part of a closed-loop control strategy. By way of example,controller 170 may be configured to evaluate the sensor signals frompressure transducer 180 and compare the pressure of the regulated flowof natural gas to the target pressure. Controller 170 may be configuredto engage solenoid 154 while the pressure observed by pressuretransducer 180 differs from the target pressure. Such a closed-loopcontrol strategy may employ a deadband pressure variation (e.g., 5 PSI).Controller 170 is configured to not engage solenoid 154 when thepressure observed by pressure transducer 180 falls within the deadbandpressure variation, according to one embodiment. Employing a deadbandpressure variation reduces actuation of solenoid 154 and limitspremature wear on the components of natural gas system 50, according toone embodiment. In other embodiments, controller 170 is configured toemploy an open-loop control strategy and engage valve 150 without regardfor the pressure of the regulated flow of natural gas.

As shown in FIG. 12, natural gas system 50 includes a sensor 182 that iscoupled to controller 170 and configured to provide sensor signals. Inone embodiment, sensor 182 is a throttle position sensor configured toprovide information relating to a requested throttle input for a vehicle(e.g., a refuse truck, a concrete mixer truck, a military truck, etc.).According to the embodiment shown in FIG. 12, controller 170 is coupledto engine 30. By way of example, controller 170 may be coupled to acontroller area network bus of engine 30 (e.g., part of an enginemanagement system). Various signals relating to an engine condition ofengine 30 may be provided to controller 170. In one embodiment, theengine condition includes at least one of a current fuel consumptiondemand, whether the engine is running lean or rich, and a signal from apost-combustion oxygen sensor.

According to one embodiment, controller 170 is configured to determinethe target pressure using information from at least one of engine 30 andsensor 182. In one embodiment, controller 170 is configured to determinethe target pressure based on the requested throttle input. By way ofexample, the target pressure may increase such that engine 30 receivesmore fuel when an operator depresses a throttle pedal. In anotherembodiment, controller 170 is configured to determine the targetpressure based on an engine condition (e.g., a current fuel consumptiondemand, etc.). In still another embodiment, controller 170 determinesthe target pressure using an offset provided by an operator. By way ofexample, an operator may manually control the target pressure or mayengage a “high idle” mode and increase the target pressure above thatrequired based the current engine conditions.

Referring next to the exemplary embodiments shown in FIGS. 13-17, avehicle, shown as refuse truck 200, includes a fuel pod 210 configuredto provide natural gas to power an engine 220. According to analternative embodiment, the vehicle is another type of vehicle (e.g., aconcrete mixer truck, a military truck, etc.). As shown in FIG. 13,refuse truck 200 includes a body assembly, shown as body assembly 230,coupled to a frame 240. According to an exemplary embodiment, bodyassembly 230 includes a plurality of sidewalls 232, an upper wall 234,and a fender panel, shown as fender 236. As shown in FIG. 13, fender 236is positioned along a lower portion of sidewall 232.

Fuel pod 210 includes a plurality of natural gas fuel tanks, accordingto an exemplary embodiment, positioned along upper wall 234 of bodyassembly 230. Fuel pod 210 is coupled to engine 220 with a plurality ofconduits that define a flow path. According to an exemplary embodiment,a fuel regulator 270 is disposed along the flow path and configured toregulate a flow of natural gas from fuel pod 210.

As shown in FIG. 13, refuse truck 200 includes a shutoff valve 250disposed along the flow path between fuel pod 210 and fuel regulator270. Shutoff valve 250 includes a lever, shown as lever 252, that isconfigured to actuate shutoff valve 250 and control the flow of naturalgas from fuel pod 210. According to an exemplary embodiment, shutoffvalve 250 is coupled to a lower portion of body assembly 230 such thatan operator standing alongside refuse truck 200 may isolate the fuel podby engaging shutoff valve 250. As shown in FIGS. 13-14, shutoff valve250 is positioned underneath fender 236.

Referring still to the exemplary embodiment shown in FIG. 13, refusetruck 10 includes a user access panel 260. As shown in FIG. 13, useraccess panel 260 is positioned along a lower portion of body assembly230 such that an operator standing alongside refuse truck 200 may engageone or more components of user access panel 260. In one embodiment, useraccess panel 260 provides a user interface, while various components ofthe natural gas system (e.g., fuel regulator 270) are positionedlaterally inboard (e.g., between frame rails of frame 240). Positioningvarious components of the natural gas system (e.g., fuel regulator 270)laterally inboard of user access panel 260 facilitates mounting stillother components along the outer surface of body assembly 230 withoutlimiting an operator's ability to control the natural gas system. Refusetruck 200 spaces large components and associated fittings of fuelregulator 270 from exposed areas of body assembly 230, thereby allowinguse of the exposed area for other purposes (e.g., to provide storage).According to an alternative embodiment, user access panel 260 ispositioned within a fuel storage unit.

Referring next to FIG. 17, user access panel 260 is disposed along aflow path between fuel pod 210 and fuel regulator 270. Fuel regulator270 is included as part of a manifold 280. In one embodiment, manifold280 is positioned near engine 220, thereby reducing the impact ofpost-regulation pressure losses and increasing the likelihood ofproviding natural gas to engine 220 at a target or preset pressure.

According an exemplary embodiment, manifold 280 includes a shutoff valve282 and a pressure transducer 284. As shown in FIG. 17, shutoff valve282 includes a normally closed solenoid valve, which allowsdisengagement of the natural gas system from engine 220. Shutoff valve282 is engaged and disengaged with a controller, according to anexemplary embodiment. Pressure transducer 284 is positioned upstream offuel regulator 270 and provides sensor signals (e.g., digital signals toa controller or gauge, analog signals to a controller or gauge, etc.)relating to the pressure of the natural gas in fuel pod 210. Pressuretransducer 284 provides a signal (e.g., a signal of between 0.5 voltsand 4.5 volts) relating to the pressure of the natural gas in fuel pod210 to a gauge positioned in a cab of refuse truck 200, according to anexemplary embodiment. According to the exemplary embodiment shown inFIG. 17, a filter 290 is positioned along the flow path between fuel pod210 and engine 220.

Referring still to FIG. 17, user access panel 260 includes ahigh-pressure fuel gauge 262, a first fuel receptacle 264 (e.g., a NGV1fuel receptacle), a second fuel receptacle 266 (e.g., a transit fillfuel receptacle), and a manual shutoff valve 268. As shown in FIG. 17,high-pressure fuel gauge 262 is an analog gauge configured to indicate afill level (e.g., a pressure) of the natural gas within fuel pod 210. Inother embodiments, high-pressure fuel gauge 262 receives a signal from apressure transducer (e.g., pressure transducer 284) and indicates a filllevel of the natural gas within fuel pod 210.

At least one of the various controllers described herein may beimplemented as a general-purpose processor, an application specificintegrated circuit (ASIC), one or more field programmable gate arrays(FPGAs), a digital-signal-processor (DSP), a group of processingcomponents, or other suitable electronic processing components. In oneembodiment, at least one of the controllers includes memory and aprocessor. The memory is one or more devices (e.g., RAM, ROM, FlashMemory, hard disk storage, etc.) for storing data and/or computer codefor facilitating the various processes described herein. The memory maybe or include non-transient volatile memory or non-volatile memory. Thememory may include database components, object code components, scriptcomponents, or any type of information structure for supporting thevarious activities and information structures described herein. Thememory may be communicably connected to the processor and providecomputer code or instructions to the processor for executing theprocesses described herein. The processor may be implemented as ageneral-purpose processor, an application specific integrated circuit(ASIC), one or more field programmable gate arrays (FPGAs), adigital-signal-processor (DSP), a group of processing components, orother suitable electronic processing components.

It is important to note that the construction and arrangement of theelements of the systems and methods as shown in the embodiments areillustrative only. Although only a few embodiments of the presentdisclosure have been described in detail, those skilled in the art whoreview this disclosure will readily appreciate that many modificationsare possible (e.g., variations in sizes, dimensions, structures, shapesand proportions of the various elements, values of parameters, mountingarrangements, use of materials, colors, orientations, etc.) withoutmaterially departing from the novel teachings and advantages of thesubject matter recited. For example, elements shown as integrally formedmay be constructed of multiple parts or elements. It should be notedthat the elements and/or assemblies of the enclosure may be constructedfrom any of a wide variety of materials that provide sufficient strengthor durability, in any of a wide variety of colors, textures, andcombinations. The order or sequence of any process or method steps maybe varied or re-sequenced, according to alternative embodiments. Othersubstitutions, modifications, changes, and omissions may be made in thedesign, operating conditions, and arrangement of the preferred and otherembodiments without departing from scope of the present disclosure orfrom the spirit of the appended claims.

The present disclosure contemplates methods, systems, and programproducts on any machine-readable media for accomplishing variousoperations. The embodiments of the present disclosure may be implementedusing existing computer processors, or by a special purpose computerprocessor for an appropriate system, incorporated for this or anotherpurpose, or by a hardwired system. Embodiments within the scope of thepresent disclosure include program products comprising machine-readablemedia for carrying or having machine-executable instructions or datastructures stored thereon. Such machine-readable media can be anyavailable media that can be accessed by a general purpose or specialpurpose computer or other machine with a processor. By way of example,such machine-readable media can comprise RAM, ROM, EPROM, EEPROM, CD-ROMor other optical disk storage, magnetic disk storage or other magneticstorage devices, or any other medium which can be used to carry or storedesired program code in the form of machine-executable instructions ordata structures and which can be accessed by a general purpose orspecial purpose computer or other machine with a processor. Wheninformation is transferred or provided over a network or anothercommunications connection (either hardwired, wireless, or a combinationof hardwired or wireless) to a machine, the machine properly views theconnection as a machine-readable medium. Thus, any such connection isproperly termed a machine-readable medium. Combinations of the above arealso included within the scope of machine-readable media.Machine-executable instructions include, for example, instructions anddata, which cause a general-purpose computer, special purpose computer,or special purpose processing machines to perform a certain function orgroup of functions.

Although the figures may show a specific order of method steps, theorder of the steps may differ from what is depicted. Also two or moresteps may be performed concurrently or with partial concurrence. Suchvariation will depend on the software and hardware systems chosen and ondesigner choice. All such variations are within the scope of thedisclosure. Likewise, software implementations could be accomplishedwith standard programming techniques with rule-based logic and otherlogic to accomplish the various connection steps, processing steps,comparison steps, and decision steps.

What is claimed is:
 1. A natural gas system for a vehicle, comprising: atank configured to provide a supply flow of natural gas; a conduitdefining a flow path, the conduit including a first end coupled to thetank and a second end configured to be coupled to an engine; a valvedisposed along the flow path, wherein the valve is configured to providea regulated flow of natural gas to the engine by adjusting the supplyflow of natural gas; an accumulator disposed along the flow pathdownstream of the valve, the accumulator having a volume between aninlet and an outlet, wherein the volume, the inlet, and the outlet forma portion of the flow path, the accumulator thereby positioned to bufferat least a portion of the variations in the flow of natural gas suchthat the engine receives a consistent flow of natural gas, wherein theaccumulator includes a movable wall, wherein an effective volume of theaccumulator varies based on the position of the movable wall; a pressuretransducer disposed along the flow path downstream of the valve, whereinthe pressure transducer is configured to provide sensor signals relatingto a pressure of the regulated flow of natural gas; and a controllerconfigured to: evaluate a target pressure for the regulated flow ofnatural gas; selectively engage the valve based on the target pressuresuch that the valve provides a pressure adjustment; monitor the sensorsignals for a fluctuation in the regulated flow of natural gas, thefluctuation comprising a pressure variation produced due to physicalinteraction of the supply flow of natural gas with at least one of theconduit and the valve; adjust the valve based on the fluctuation suchthat the engine receives natural gas at the target pressure; and varythe position of the movable wall in response to the pressure of theregulated flow of natural gas.
 2. The system of claim 1, wherein thecontroller is configured to evaluate the sensor signals and compare thepressure of the regulated flow of natural gas to the target pressure. 3.The system of claim 2, wherein the valve includes a solenoid positionedto engage a movable valve element, wherein the pressure of the regulatedflow of natural gas varies based on the position of the movable valveelement.
 4. The system of claim 2, further comprising a throttleposition sensor configured to provide information relating to arequested throttle input, wherein the controller is configured todetermine the target pressure based on the requested throttle input. 5.The system of claim 2, wherein the controller is configured to determinethe target pressure based on an engine condition.
 6. The system of claim1, wherein the movable wall comprises a flexible bladder.
 7. The systemof claim 6, further comprising an actuator operatively coupled to thecontroller, wherein the controller is configured to engage the actuatorto selectively reposition the flexible bladder by at least one ofinflating and deflating the bladder.
 8. The system of claim 1, whereinthe movable wall comprises a rigid wall.
 9. The system of claim 8,further comprising an actuator operatively coupled to the controller,wherein the controller is configured to engage the actuator toselectively reposition the rigid wall.